How to get split matel plate effect?
I have done this by modeling the whole object as one, and then as a final step I set up planes where I wanted cuts.
The add-on BoolTool lets you do a Slice operation which will quickly cut along a plane.

This was the result in rendered view:

It takes some planning with all-quad geometry.  Since you're dividing along a plane, you're essentially adding one loop cut somewhere which should lead to quads on either side.  There is a BIG problem if you have any poles.  It looks terrible.  For this object it wasn't a problem, it's modeled for subdivision and the pole is hidden.  With some planning I think the body of a rocket would be possible.